Lightning strike dispersion for composite aircraft structures

ABSTRACT

A lightning strike dispersion structure may include a composite component having an outboard surface, wherein the composite component is electrically nonconductive. The lightning strike dispersion structure may include a metal sheet coupled to and extending across a minority portion of the outboard surface of the composite component, wherein the metal sheet is electrically conductive. The lightning strike dispersion structure may also include a metal stud coupled to and in electrical contact with the metal sheet, the metal stud extending completely through the composite component, wherein the metal stud is electrically conductive.

FIELD

The present disclosure relates to systems and methods for lightningstrike dispersion, and more specifically, to transferring electricityreceived by an aircraft from a lightning strike.

BACKGROUND

Certain components of an aircraft, such as packboards, are oftenconstructed from composite materials. Such composite elements are oftenelectrically nonconductive and thus prevent or at least hinder thetransfer of electricity to a main electrical ground of an aircraft inthe event of a lightning strike or other similar event. Further, becausethe composite elements are electrically nonconductive, a lightningstrike could damage the composite element and/or the contents of thecomposite element, thus adversely affecting the performance and safetyof the aircraft.

SUMMARY

In various embodiments, a lightning strike dispersion structure isdisclosed. The lightning strike dispersion structure may include acomposite component having an outboard surface, wherein the compositecomponent is electrically nonconductive. The lightning strike dispersionstructure may include a metal sheet coupled to and extending across aminority portion of the outboard surface of the composite component,wherein the metal sheet is electrically conductive. The lightning strikedispersion structure may also include a metal stud coupled to and inelectrical contact with the metal sheet, the metal stud extendingcompletely through the composite component, wherein the metal stud iselectrically conductive.

In various embodiments, the lightning strike dispersion structure mayalso include a metal mesh coupled to and extending across a majorityportion of the outboard surface of the composite component, wherein themetal mesh is electrically conductive and the majority portion of theoutboard surface of the composite component is inclusive of the minorityportion of the outboard surface of the composite component such that themetal mesh extends across and is in electrical contact with the metalsheet.

In various embodiments, the metal mesh may be in direct physical contactwith the metal sheet. In various embodiments, the majority portion ofthe outboard surface of the composite component may have a surface areathat is at least 10 times larger than a surface area of the minorityportion of the outboard surface of the composite component. In variousembodiments, the metal mesh is embedded in an exterior surface materialof an aircraft. In various embodiments, the minority portion of theoutboard surface of the composite component has a surface area that isat least 2 times larger than a cross-sectional area of a head of themetal stud.

In various embodiments, the metal stud, when coupled to the metal sheet,may be non-rotatable about a longitudinal axis of the metal stud. Themetal stud may be a self-clinching stud that is coupled to the metalsheet. In various embodiments, a head of the metal stud is flush with asurface of the metal sheet. The metal stud may be permanently integratedwith the composite component.

In various embodiments, a longitudinal axis of the metal stud extendsperpendicular to plies of the composite component. In variousembodiments, the metal stud may be non-structural and thus may be freeof a structural load. The minority portion of the outboard surface ofthe composite component may have a surface area that is about 1 squareinch.

In various embodiments, a packboard of an aircraft is disclosed. Thepackboard may include a composite housing having an inboard surface andan outboard surface, wherein the composite housing is electricallynonconductive. The packboard may also include a metal sheet coupled toand extending across a minority portion of the outboard surface of thecomposite housing, wherein the metal sheet is electrically conductive.The packboard may also include a metal stud comprising a head and a tiplongitudinally opposite the head. The metal stud may be electricallyconductive and may extend through the composite housing. The head of themetal stud may be coupled to and in electrical contact with the metalsheet and the tip of the metal stud may protrude from the inboardsurface of the composite housing. Further, the tip of the metal stud maybe configured to be electrically connected to an electrical ground ofthe aircraft.

In various embodiments, the packboard further includes a metal meshcoupled to and extending across a majority portion of the outboardsurface of the composite housing, wherein the metal mesh is electricallyconductive and the majority portion of the outboard surface of thecomposite housing is inclusive of the minority portion of the outboardsurface of the composite housing such that the metal mesh extends acrossand is in electrical contact with the metal sheet. In variousembodiments, at least the tip of the metal stud may be threaded and maybe configured to couple with a threaded nut for electrically connectingthe metal stud to the electrical ground of the aircraft. In variousembodiments, the metal stud may be permanently integrated with thecomposite housing.

In various embodiments, a method of manufacturing a packboard isdisclosed. The method may include coupling a head of a metal stud thatis electrically conductive to a metal sheet that is electricallyconductive such that the metal stud is in electrical contact with themetal sheet and the head of the metal stud is substantially flush with afirst surface of the metal sheet. The method may also include layingplies of electrically nonconductive material across a second surface,opposite the first surface, of the metal sheet. Laying the plies mayinclude molding the plies to shape a packboard housing form having aninboard surface and an outboard surface, the second surface of the metalsheet extending across a minority portion of the outboard surface of thepackboard housing form. Laying the plies may also include extending themetal stud completely through the plies and coupling a metal mesh thatis electrically conductive across the first surface of the metal sheetand across a majority portion of the outboard surface of the packboardhousing form, wherein the metal mesh is in electrical contact with thefirst surface of the metal sheet. The method may further include curingthe plies to set the packboard housing form.

In various embodiments, coupling the head of the metal stud to the metalsheet occurs before laying the plies and before curing the plies. Invarious embodiments, a longitudinal axis of the metal stud is maintainedperpendicular to the plies while laying the plies.

The forgoing features and elements may be combined in variouscombinations without exclusivity, unless expressly indicated hereinotherwise. These features and elements as well as the operation of thedisclosed embodiments will become more apparent in light of thefollowing description and accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The subject matter of the present disclosure is particularly pointed outand distinctly claimed in the concluding portion of the specification. Amore complete understanding of the present disclosure, however, may bestbe obtained by referring to the detailed description and claims whenconsidered in connection with the following illustrative figures. In thefollowing figures, like reference numbers refer to similar elements andsteps throughout the figures.

FIG. 1 illustrates a perspective view of an aircraft having an exteriormounted composite component, in accordance with various embodiments;

FIG. 2 illustrates a perspective view of a packboard, in accordance withvarious embodiments;

FIG. 3 illustrates a side view of the packboard of FIG. 2, in accordancewith various embodiments;

FIG. 4 illustrates a cross-section view of a metal stud extendingthrough an exterior mounted composite component, in accordance withvarious embodiments;

FIG. 5 illustrates a partial perspective view of a metal stud coupled toa metal sheet, in accordance with various embodiments;

FIG. 6 illustrates a perspective view of an electrically conductivecable coupled to the metal stud, in accordance with various embodiments;and

FIG. 7 illustrates a schematic flow chart diagram of a method formanufacturing a packboard, in accordance with various embodiments.

Elements and steps in the figures are illustrated for simplicity andclarity and have not necessarily been rendered according to anyparticular sequence. For example, steps that may be performedconcurrently or in different order are illustrated in the figures tohelp to improve understanding of embodiments of the present disclosure.

DETAILED DESCRIPTION

The detailed description of exemplary embodiments herein makes referenceto the accompanying drawings, which show exemplary embodiments by way ofillustration. While these exemplary embodiments are described insufficient detail to enable those skilled in the art to practice thedisclosures, it should be understood that other embodiments may berealized and that logical changes and adaptations in design andconstruction may be made in accordance with this disclosure and theteachings herein. Thus, the detailed description herein is presented forpurposes of illustration only and not of limitation.

The scope of the disclosure is defined by the appended claims and theirlegal equivalents rather than by merely the examples described. Forexample, the steps recited in any of the method or process descriptionsmay be executed in any order and are not necessarily limited to theorder presented. Furthermore, any reference to singular includes pluralembodiments, and any reference to more than one component or step mayinclude a singular embodiment or step. Also, any reference to tacked,attached, fixed, coupled, connected or the like may include permanent,removable, temporary, partial, full and/or any other possible attachmentoption. Additionally, any reference to without contact (or similarphrases) may also include reduced contact or minimal contact. Surfaceshading lines may be used throughout the figures to denote differentparts but not necessarily to denote the same or different materials.Different cross-hatching is used throughout the figures to denotedifferent parts but not necessarily to denote the same or differentmaterials.

FIG. 1 illustrates a perspective view of an aircraft 5 having anexterior mounted composite component 10, in accordance with variousembodiments. Referring to FIG. 1, an exemplary aircraft 5 is shown, inaccordance with various embodiments. Aircraft 5 may include a fuselagewith wings fixed to the fuselage. An emergency exit door 6 may bedisposed on the fuselage to allow passengers to exit the aircraft 5.Although not depicted in FIG. 1, the emergency exit door 6, in variousembodiments, may be situated over the wings of the aircraft 5 such thatpassengers exiting through the emergency exit door 6 can exit onto thewing(s). The exterior mounted composite component 10 may be, forexample, a packboard 100 (with brief reference to FIG. 2) configured tostore an evacuation slide assembly. In various embodiments, thecomposite component 10 may be a panel or other exterior mountedcomposite structure of the aircraft 5.

As used herein, the term composite component 10 refers to anelectrically nonconductive structure. Electrically nonconductiveelements disposed on or near the exterior of the aircraft 5 may presentperformance or safety liabilities in the event of a lightning strike.Accordingly, the present disclosure relates to transferring electricityfrom the exterior of the aircraft 5, through the electricallynonconductive composite component 10, and to the main electrical groundof the aircraft 5.

As used herein, the term “composite” refers to layers or fibers set in aresin matrix. In other words, the term “composite” may refer to carbonfibers, glass fibers, aramid fibers, and/or plastic fibers, amongothers, held together and set in a resin or epoxy matrix.

In various embodiments, and with reference to FIGS. 2 and 3, a lightningstrike dispersion structure 105 for a packboard 100 is disclosed. Thelightning strike dispersion structure 105 includes various components,described below in greater detail, that facilitate the transfer ofelectricity through the packboard 100 to the main electrical ground ofthe aircraft 5. As mentioned above, the packboard 100 may be afuselage-mounted container within which, for example, an evacuationslide assembly is housed. In other words, the packboard 100 generallydefines a chamber 116 for storing and/or housing one or more items orassemblies. In various embodiments, an access panel may extend acrossthe opening of the chamber 116 to retain the contents of the packboard100. In various embodiments, for example, an evacuation slide assemblymay jettison the access panel and deploy the inflatable evacuation slidein response to the emergency exit door 6 opening.

The lightning strike dispersion structure 105 for the packboard 100includes a composite housing 110, a metal sheet 120 (with reference toFIG. 4), a metal mesh 130 (with reference to FIG. 4), and a metal stud150 (with reference to FIG. 4). These components are described ingreater detail below. Throughout the present disclosure, the terms“composite component 10,” “packboard 100,” and “composite housing 110”refer to electrically nonconductive material. That is, the term“packboard 100” specifically refers to one type of “composite component10” and the term “composite housing 110” specifically refers to thestructural body that forms and defines the chamber 116 of the packboard100. Thus, while numerous details and various embodiments are includedherein with reference to a packboard 100, it is recognized that thelightning strike dispersion subject matter of the present disclosure maybe applied and implemented with other, non-packboard-type compositecomponents 10.

The metal sheet 120, the metal mesh 130, and the metal stud 150 may bemade from electrically conductive metal materials. For example, themetal sheet 120, the metal mesh 130, and the metal stud 150 may be madefrom aluminum, steel, copper, nickel, tin, brass, tungsten, or iron,among others, or alloys thereof. The metal sheet 120, the metal mesh130, and the metal stud 150 may be the same material or they may bedifferent.

The packboard 100 has an inboard surface 112 (with reference to FIG. 3)and an outboard surface 114. The term “outboard surface 114” refers tosurfaces of the packboard 100 that are disposed exterior to the aircraft5 while the term “inboard surface” refers to surfaces of the compositecomponent 10 that are not disposed exterior to the aircraft. Forexample, the inboard surface 112 refers to surfaces that are disposedand/or face inward relative to the exterior skin of the aircraft. Invarious embodiments, the metal stud 150 extends through the compositehousing 110 of the packboard 100 from the outboard surface 114 to theinboard surface 112. The metal stud 150 is electrically conductive.

In various embodiments, and with reference to FIGS. 4 and 5, furtherdetails of the lightning strike dispersion structure 105 areillustrated. FIG. 4 illustrates a cross-section view of the metal stud150 extending through the composite housing 110. While FIG. 4 shows thecomposite housing 110 having two layers, in various embodiments thecomposite housing 110 may have more than two layers of compositematerial. In various embodiments, the metal stud 150 may include a head152 and a tip 154.

In various embodiments, the metal sheet 120 is disposed adjacent aportion of the outboard surface 114 of the composite housing 110. Invarious embodiments, the head 152 of the metal stud 150 may be directlycoupled to the metal sheet 120. For example, the metal stud 150 may be aself-clinching fastener and the head 152 of the metal stud 150 may bemounted and/or fixed to the metal sheet 120 so as to be non-rotatableabout a longitudinal axis of the metal stud 150. In various embodiments,the metal sheet 120 may be a ductile material that allows the head 152of the metal stud 150 to be non-rotatably embedded in the metal sheet120. In various embodiments, the head 152 of the metal stud 150 issubstantially flush with an exterior facing surface of the metal sheet120.

In various embodiments, and as described in more detail below withreference to FIG. 7, the metal stud 150 may be permanently integratedwith the metal sheet 120 and/or the composite housing 110 during themanufacture of the packboard 100. In various embodiments, the metal stud150 may be non-structural and thus may not support a structural load. Inother words, the packboard 100 may be mechanically and structurallycoupled to the aircraft 5 via fasteners or weldments other than themetal stud 150.

The metal sheet 120 is electrically conductive and, according to variousembodiments, may extend across a minority portion of the outboardsurface 114 of the composite housing 110. In other words, the term“minority portion” refers to the portion (e.g., part of a whole) of theoutboard surface 114 of the composite housing 110 across which the metalsheet 120 is disposed and thus also refers to the areal dimensions of asurface of the metal sheet 120 extending parallel to the outboardsurface 114. In various embodiments, the minority portion may be lessthan half the outboard surface 114 of the composite housing 110. Invarious embodiments, the minority portion may be between about 0.5 and25 square inches. In various embodiments, the minority portion may bebetween about 1 and 9 square inches. In various embodiments, theminority portion may be about 1 square inch. In various embodiments, theminority portion of the outboard surface 114 of the composite housing110 has a surface area that is at least 2 times larger than across-sectional area of the head 152 of the metal stud.

The metal mesh 130 is electrically conductive and, according to variousembodiments, extends across a majority portion of the outboard surface114 of the composite housing 110. The term “majority portion” refers tothe portion (e.g., part of a whole) of the outboard surface 114 of thecomposite housing 110 across which the metal mesh 130 is disposed andthus also refers to the areal dimensions of a surface of the metal mesh130 extending parallel to the outboard surface 114. The majority portionis inclusive of the minority portion. That is, according to variousembodiments, the metal mesh 130 overlaps the metal sheet 120 so that themetal mesh 130 is in electrical contact with the metal sheet 120. Invarious embodiments, the metal mesh 130 is in direct physical contactwith the metal sheet 120.

In various embodiments, the majority portion may be more than half ofthe outboard surface 114 of the composite housing 110 and thus the metalmesh 130 may extend across more than half of the exterior surface areaof the composite housing 110. In various embodiments, the majorityportion of the outboard surface 114 has a surface area that is at least10 times larger than a surface area of the minority portion of theoutboard surface 114.

In various embodiments, the metal mesh 130 may extend acrosssubstantially the entire outboard surface 114 of the composite housing110. In various embodiments, the metal mesh 130 may be coupled withand/or embedded into an outer coating, skin, or paint. In variousembodiments, the metal mesh 130 may electrically connect with or may becontinuous with a similar metal mesh that extends across the exteriorsurface of the aircraft 5 for lightning strike electricity dispersion.Thus, electricity from a lightning strike may conduct through the metalmesh 130, through the metal sheet 120, through the metal stud 150, andto the main electrical ground of the aircraft 5. Thus, the metal sheet120 may facilitate electrical conduction between the metal stud 150 andthe metal mesh 130. The metal sheet 120 may also provide a secure mediumto which the metal stud 150 is non-rotatably affixed.

In various embodiments, and with reference to FIG. 6, an electricallyconductive cable 166 for electrically connecting the tip 154 (or atleast a portion of tip 154) of the metal stud 150 with the mainelectrical ground 168 of the aircraft 5 is disclosed. FIG. 6 illustratesa partial view of the inboard surface 112 of the composite housing 110.Extending from the inboard surface 112 of the composite housing 110 isthe tip 154 of the metal stud 150. In various embodiments, the tip 154of the metal stud 150 may be threaded and one or more threaded nuts 161,162 may be threadably engaged on the metal stud 150. For example, theelectrically conductive cable 166 may have a coupler 164 that engagesthe tip 154 of the metal stud 150 and the threaded nut(s) 161, 162 maysecure the coupler 164 in place to maintain the electrical connectionbetween the electrically conductive cable 166 and the metal stud 150. Invarious embodiments, a nut may retain the coupler 164 of theelectrically conductive cable 166 between the nut and the inboardsurface 112 of the composite housing 110. In various embodiments, thecoupler 164 may be retained coupled to the metal stud 150 between one ormore nuts.

FIG. 7 illustrates a schematic flow chart diagram of a method 790 formanufacturing the packboard 100, in accordance with various embodiments.The method 790 may include coupling the head 152 of the metal stud 150to the metal sheet 120 such that the metal stud 150 is in electricalcontact with the metal sheet 120 and the head 152 of the metal stud 150is substantially flush with a first surface of the metal sheet 120 (step792). The method 790 may further include laying plies of electricallynonconductive material across a second surface, opposite the firstsurface, of the metal sheet 120 (step 794). According to variousembodiments, laying the plies includes molding the plies to shape apackboard housing form having an inboard surface and an outboardsurface. The second surface of the metal sheet 120 may extend across aminority portion of the outboard surface of the packboard housing form.Laying the plies may also include extending the metal stud 150completely through the plies.

The method 790 further includes, according to various embodiments,coupling the metal mesh 130 across the first surface of the metal sheet120 and across a majority portion of the outboard surface of thepackboard housing form, wherein the metal mesh 130 is in electricalcontact with the first surface of the metal sheet 120 (step 796). Themethod 790 also includes curing the plies to set the packboard housingform (step 798).

In various embodiments, coupling the head 152 of the metal stud 150 tothe metal sheet 120 (step 792) occurs before laying the plies (step 794)and before curing the plies (step 798). In various embodiments,extending the metal stud 150 completely through the plies occurs as theplies are being laid and before the plies are cured (step 798). Invarious embodiments, a longitudinal axis of the metal stud 150 ismaintained perpendicular to the plies while laying the plies (step 794).

Benefits, other advantages, and solutions to problems have beendescribed herein with regard to specific embodiments. Furthermore, theconnecting lines shown in the various figures contained herein areintended to represent exemplary functional relationships and/or physicalcouplings between the various elements. It should be noted that manyalternative or additional functional relationships or physicalconnections may be present in a practical system. However, the benefits,advantages, solutions to problems, and any elements that may cause anybenefit, advantage, or solution to occur or become more pronounced arenot to be construed as critical, required, or essential features orelements of the disclosures. The scope of the disclosures is accordinglyto be limited by nothing other than the appended claims and their legalequivalents, in which reference to an element in the singular is notintended to mean “one and only one” unless explicitly so stated, butrather “one or more.” Moreover, where a phrase similar to “at least oneof A, B, or C” is used in the claims, it is intended that the phrase beinterpreted to mean that A alone may be present in an embodiment, Balone may be present in an embodiment, C alone may be present in anembodiment, or that any combination of the elements A, B and C may bepresent in a single embodiment; for example, A and B, A and C, B and C,or A and B and C.

Systems, methods and apparatus are provided herein. In the detaileddescription herein, references to “various embodiments”, “oneembodiment”, “an embodiment”, “an example embodiment”, etc., indicatethat the embodiment described may include a particular feature,structure, or characteristic, but every embodiment may not necessarilyinclude the particular feature, structure, or characteristic. Moreover,such phrases are not necessarily referring to the same embodiment.Further, when a particular feature, structure, or characteristic isdescribed in connection with an embodiment, it is submitted that it iswithin the knowledge of one skilled in the art to affect such feature,structure, or characteristic in connection with other embodimentswhether or not explicitly described. After reading the description, itwill be apparent to one skilled in the relevant art(s) how to implementthe disclosure in alternative embodiments.

Furthermore, no element, component, or method step in the presentdisclosure is intended to be dedicated to the public regardless ofwhether the element, component, or method step is explicitly recited inthe claims. No claim element herein is to be construed under theprovisions of 35 U.S.C. 112(f), unless the element is expressly recitedusing the phrase “means for.” As used herein, the terms “comprises”,“comprising”, or any other variation thereof, are intended to cover anon-exclusive inclusion, such that a process, method, article, orapparatus that comprises a list of elements does not include only thoseelements but may include other elements not expressly listed or inherentto such process, method, article, or apparatus.

What is claimed is:
 1. A lightning strike dispersion structurecomprising: a composite component having an outboard surface, whereinthe composite component is electrically nonconductive; a metal sheetcoupled to and extending across a minority portion of the outboardsurface of the composite component, wherein the metal sheet iselectrically conductive and comprises a ductile material; a metal studcoupled to and in electrical contact with the metal sheet, the metalstud extending completely through the composite component, wherein themetal stud comprises a head and a tip longitudinally opposite the head,wherein the metal stud is electrically conductive and the head of themetal stud is fixedly embedded in the ductile material of the metalsheet; and a metal mesh coupled to and extending across a majorityportion of the outboard surface of the composite component, wherein themetal mesh is electrically conductive and the majority portion of theoutboard surface of the composite component is inclusive of the minorityportion of the outboard surface of the composite component such that themetal mesh extends across and is in electrical contact with the metalsheet.
 2. The structure of claim 1, wherein the metal mesh is in directphysical contact with the metal sheet.
 3. The structure of claim 1,wherein the majority portion of the outboard surface of the compositecomponent has a surface area that is at least 10 times larger than asurface area of the minority portion of the outboard surface of thecomposite component.
 4. The structure of claim 1, wherein the metal meshis embedded in an exterior surface material of an aircraft.
 5. Thestructure of claim 1, wherein the minority portion of the outboardsurface of the composite component has a surface area that is at least 2times larger than a cross-sectional area of a head of the metal stud. 6.The structure of claim 1, wherein the metal stud, when coupled to themetal sheet, is non-rotatable about a longitudinal axis of the metalstud.
 7. The structure of claim 1, wherein the head of the metal stud isa self-clinching head that is coupled to the metal sheet.
 8. Thestructure of claim 1, wherein a head of the metal stud is flush with asurface of the metal sheet.
 9. The structure of claim 1, wherein themetal stud is permanently integrated with the composite component. 10.The structure of claim 1, wherein a longitudinal axis of the metal studextends perpendicular to plies of the composite component.
 11. Thestructure of claim 1, wherein the metal stud is non-structural and thusis free of a structural load.
 12. The structure of claim 1, wherein theminority portion of the outboard surface of the composite component hasa surface area that is about 1 square inch.
 13. A packboard of anaircraft, the packboard comprising: a composite housing comprising aninboard surface and an outboard surface, wherein the composite housingis electrically nonconductive; a metal sheet coupled to and extendingacross a minority portion of the outboard surface of the compositehousing, wherein the metal sheet is electrically conductive andcomprises a ductile material; and a metal stud comprising a head and atip longitudinally opposite the head, wherein: the metal stud iselectrically conductive; the metal stud extends through the compositehousing; the head of the metal stud is fixedly embedded in the ductilematerial of the metal sheet such that the metal stud is coupled to andin electrical contact with the metal sheet; the tip of the metal studprotrudes from the inboard surface of the composite housing; and the tipof the metal stud is configured to be electrically connected to anelectrical ground of the aircraft.
 14. The packboard of claim 13,further comprising a metal mesh coupled to and extending across amajority portion of the outboard surface of the composite housing,wherein the metal mesh is electrically conductive and the majorityportion of the outboard surface of the composite housing is inclusive ofthe minority portion of the outboard surface of the composite housingsuch that the metal mesh extends across and is in electrical contactwith the metal sheet.
 15. The packboard of claim 13, wherein at leastthe tip of the metal stud is threaded and is configured to couple with athreaded nut for electrically connecting the metal stud to theelectrical ground of the aircraft.
 16. The packboard of claim 13,wherein the metal stud is permanently integrated with the compositehousing.